Janse, a Human from the planet Ukio, was employed by BlasTech Industries as an evaluator of weapons designs throughout the duration of the Galactic Civil War. He later honed his skills and became known as a sharpshooter. After his time with BlasTech, Janse departed with a supply of A280 blaster rifles and enlisted with the Alliance to Restore the Republic just before the Battle of Endor in 4 ABY, obtaining the rank of corporal within Alliance Special Forces. Janse's responsibilities included serving as a scout during hunting operations. In that year, Janse was present at a strategic meeting held on the Alliance Fleet's flagship, the Mon Calamari Star Cruiser known as Home One, where the Alliance strategized their assault on the Galactic Empire's second Death Star battle station in orbit around the Forest Moon of Endor. Janse was chosen as a sharpshooter within the strike team tasked with infiltrating the moon and disabling the Imperial shield generator protecting the Death Star. The team successfully took out the generator, which paved the way for Alliance starfighters to obliterate the Death Star.
During the Galactic Civil War, Janse, a Human, originated from the planet of Ukio. He eventually became skilled as a sharpshooter. He was employed as a weapons design evaluator by BlasTech Industries, a manufacturer of armaments. Ultimately, Janse departed from BlasTech, taking a number of A280 blaster rifles.
Shortly before the Battle of Endor in the year 4 ABY, Janse joined the Alliance to Restore the Republic and achieved the rank of corporal within Alliance Special Forces. By that time, he was a former sharpshooter who served as a scout during hunting missions.
In 4 ABY, Janse was present at a briefing on the Alliance Fleet's flagship, the MC80 Home One type Star Cruiser called Home One. During this briefing, Mon Mothma, the Supreme Commander of the Alliance, outlined the strategy for attacking the Galactic Empire's second Death Star battle station positioned in orbit above the Forest Moon of Endor. General Crix Madine, the Alliance commander responsible for planning the assault, detailed how members of a strike team led by General Han Solo would infiltrate Endor to disable the SLD-26 planetary shield generator on the moon. This shield was protecting the Death Star from a direct attack, which would then allow Alliance starfighters to destroy the station's main reactor. Janse was among the strike team members, serving alongside Lieutenant Greeve as a reactivated sharpshooter.
Janse and the rest of the strike team traveled to the Endor system aboard the stolen Imperial Lambda-class T-4a shuttle Tydirium, with Solo acting as the pilot. When the Super Star Destroyer Executor in defensive orbit over Endor questioned them, Solo provided a stolen Imperial code. The Executor then granted the shuttle permission to land on the Forest Moon. Shortly after landing, the strike team waited as Solo and the command crew—Luke Skywalker, Leia Organa, and the Wookiee Chewbacca—scouted the area to ensure it was safe. During this scouting, Solo inadvertently alerted a scout trooper patrol to the strike team's presence, leading to a speeder bike chase involving Skywalker, Organa, and several Imperial scouts.
Janse and the rest of the squad waited until only Skywalker returned. When it became clear that Organa was missing, Solo took the rest of the command crew to search for her, ordering the squad to continue on and rendezvous at the deflector shield generator at 0300 hours. Major Bren Derlin, the strike team's commanding officer, led the squad toward the shield generator. The squad encountered Imperial patrols several times along the way and managed to remain hidden. However, Corporal Delevar, the team's medic, nearly compromised their position by attempting to take a shot at a speeder bike; Derlin stopped him and issued a reprimand.
As night fell, Janse and the squad set up camp in a camouflaged shallow ravine, posting two sentries and establishing a blanket grid using their scanning equipment. Shortly after the squad members began their first sleeping shift, the scanners detected an All Terrain Scout Transport walker approaching their location. Derlin ordered the team to take cover, but when it was clear the walker would not pass them by, Corporal Dansra Beezer jammed its transmissions. Lieutenant Greeve used his A280 blaster rifle to precisely destroy both of the walker's spotlights, and the squad circled the walker to keep it off balance. When the AT-ST began firing randomly into the trees and foliage, Delevar fired a smoke canister into its cockpit window. The resulting explosion forced the walker pilots to abandon the vehicle and surrender to the strike team. The squad captured the pilots and forced them to make a comm check-in at blasterpoint.
The squad continued to the rendezvous point, forcing the walker pilot to make several more check-ins along the way to explain the scout walker's absence. By the time the strike team reunited, Solo and the command crew had formed an alliance with the native Ewok tribe from Bright Tree Village, who showed the strike team a path to the shield generator bunker's back door. The strike team infiltrated the bunker to destroy it with 7-PrG proton grenades; however, they were ambushed and led outside the bunker by Tempest Force, the Imperial Army legion stationed on the moon.
The strike team's capture was only temporary, as the Ewoks attacked the Imperial troops and the strike team fought back, eventually turning the tide of the battle in the Rebels' favor. The surviving members of the strike team ultimately destroyed the shield generator bunker with their proton grenades, allowing the Alliance Fleet to destroy the Death Star as planned.
Janse and the rest of the Endor strike team were equipped with basic commando gear, including a standard comlink, a low-feedback scanner, a sensor scrambler, a heavily muffled blaster, and full-forest-camouflage fatigues. As one of the strike team's sharpshooters, Janse, along with Greeve, used the A280 blaster rifles he had taken with him from BlasTech during the Battle of Endor.
Janse made his first appearance as a background Rebel character during the Home One briefing in 1983's Star Wars: Episode VI Return of the Jedi. In June 1999, Janse was given a name and a brief backstory in the Endor Limited expansion set of Decipher's Star Wars Customizable Card Game.